change color of icon css
<style>
#icon{
font-size:50px;
color:red;
transition-duration:.6s;
}
</style>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<i onclick='this.style.color="blue"' id='icon' class='fa fa-home'></i>
Click the icon.